Thursday, July 17, 2014

New paper finds only ~3.75% of atmospheric CO2 is man-made from burning of fossil fuels

CORRECTED POST of "New paper finds only ~3.75% of atmospheric CO2 is man-made from burning of fossil fuels":

Thanks to notification from and email conversations with the lead author Denica Bozhinova of the paper "Simulating the integrated summertime Δ14CO2 signature from anthropogenic emissions over Western Europe, the claim made in the original Hockey Schtick post that ~3.75% of background atmospheric CO2 is man-made from burning of fossil fuels is hereby retracted due to a misinterpretation of the paper. The author has clarified that her paper does not address the mole fraction or concentration of CO2 of fossil fuel origin present in background levels of CO2, it addresses the mole fraction or concentration of CO2 of fossil fuel origin of recent emissions only. Regarding the conclusion of the paper which states in part

"...the 6-month average CO2ff concentrations in the lower 1 km of the atmosphere across Western Europe are between 1 to 18 ppm."

I asked the author via email

"My understanding now is that CO2ff in your paper is referring to the concentration of CO2ff that is above background levels of CO2 rather than absolute concentrations of CO2ff, thus please confirm my understanding is correct that your conclusion may be stated as "...the 6-month average [CO2 concentrations of fossil-fuel origin that are above background concentrations of CO2] in the lower 1 km of the atmosphere across Western Europe are between 1 to 18 ppm," and that it is not possible to determine from your data the absolute concentrations of CO2 of fossil fuel origin [background + recently added]."

and the lead author has replied in her 3rd email today

"Your last paragraph describing the complicated fossil fuel/background relationship used in study is in fact totally correct. I am sorry that probably it is not going to be of use for your draft, however I am certain that there are other studies that investigate the issue you were trying to address."

I apologize for my misinterpretation of the paper, putting the post in draft mode during email conversations back and forth with the author, and all subsequent confusion which I caused. I'd like to thank lead author Denica Bozhinova for her kind and detailed emails [portions below], apologize for the time she has spent correcting my misinterpretation and that of several others in the blogosphere, and wish her all the best in her future career and research. Original post follows with retracted portions, along with the abstract and conclusions from the paper:A paper published today in Atmospheric Chemistry and Physics finds that only about 3.75% [15 ppm] of the CO2 in the lower atmosphere is man-made from the burning of fossil fuels, and thus, the vast remainder of the 400 ppm atmospheric CO2 is from land-use changes and natural sources such as ocean outgassing and plant respiration.According to the authors,

We find that the average gradients of fossil fuel CO2 in the lower 1200 meters of the atmosphere are close to 15 ppm at a 12 km × 12 km horizontal resolution.

D. Bozhinova1, M. K. van der Molen1, I. R. van der Velde1, M. C. Krol1,2, S. van der Laan3, H. A. J. Meijer3, and W. Peters11Meteorology and Air Quality Group, Wageningen University, the Netherlands2Institute for Marine and Atmospheric Research Utrecht, Utrecht, the Netherlands3Centre for Isotope Research, University of Groningen, Groningen, the NetherlandsAbstract.Radiocarbon dioxide (14CO2, reported in Δ14CO2) can be used to determine the fossil fuel CO2 addition to the atmosphere, since fossil fuel CO2 no longer contains any 14C. After the release of CO2 at the source, atmospheric transport causes dilution of strong local signals into the background and detectable gradients of Δ14CO2 only remain in areas with high fossil fuel emissions. This fossil fuel signal can moreover be partially masked by the enriching effect that anthropogenic emissions of 14CO2 from the nuclear industry have on the atmospheric Δ14CO2 signature. In this paper, we investigate the regional gradients in 14CO2 over the European continent and quantify the effect of the emissions from nuclear industry. We simulate the emissions and transport of fossil fuel CO2and nuclear 14CO2 for Western Europe using the Weather Research and Forecast model (WRF-Chem) for a period covering 6 summer months in 2008. We evaluate the expected CO2 gradients and the resulting Δ14CO2 in simulated integrated air samples over this period, as well as in simulated plant samples.

We find that the average gradients of fossil fuel CO2 in the lower 1200 m of the atmosphere are close to 15 ppm at a 12 km × 12 km horizontal resolution. The nuclear influence on Δ14CO2 signatures varies considerably over the domain and for large areas in France and the UK it can range from 20 to more than 500% of the influence of fossil fuel emissions. Our simulations suggest that the resulting gradients in Δ14CO2 are well captured in plant samples, but due to their time-varying uptake of CO2, their signature can be different with over 3‰ from the atmospheric samples in some regions. We conclude that the framework presented will be well-suited for the interpretation of actual air and plant 14CO2 samples.

Excerpts from the conclusions:In this work, we demonstrated the ability of our modelingframework to simulate the atmospheric transport of CO2and consequently the atmospheric 114CO2 signature in integratedair and plant samples in Western Europe. Based onour results we reach the following conclusions.1. Simulated spatial gradients of 114CO2 are of measurablesize and the 6-month average CO2ff [CO2 from the burning of fossil fuels] concentrations in the lower 1 km of the atmosphereacross Western Europe are between 1 to 18 ppm.2. Enrichment by 14CO2 from nuclear sources can partlymask the Suess effect close to nuclear emissions, particularlyin large parts of UK and northwestern France.This is consistent with previous studies (Graven andGruber, 2011) and we show that in these regions thestrength of the nuclear influence can exceed the influencefrom fossil fuel emissions.3. The simulated plant 114CO2 signatures show spatialgradients consistent with the simulated atmosphericgradients. Plant growth variability induces differencesbetween the simulated plant and the daytime atmosphericmean for the period of growth, of a magnitudethat is mostly within the measurement precision of±2 ‰, but can be up to ±7‰ in some areas.4. Integrated 114CO2 samples from areas outside the immediateenrichment area of nuclear emission sourcesare not sensitive to occasional advection of enriched airdue to their long absorption period. However, to properlyaccount for the nuclear enrichment term on smallertime scales, improvements in temporal profiles of nuclearemissions are needed.5. New 114CO2 sampling strategies should take advantageof different sampling methods, as their combineduse will provide a more comprehensive picture of theatmospheric 114CO2 temporal and spatial distribution.Additional details from selected excerpts of email conversations with the lead author Denica Bozhinova:

From the author:

...The background term in our equations, as I tried to explain in my reply on the Hockey Schtick, includes all the CO2 and its respective ∆bg signature that has been in the atmosphere before our simulation start or has been transported into our modeled area from outside during the simulation. As such it combines all the previously emitted and transported anthropogenic and natural CO2 and in our study we cannot distinguish the fractions that can be attributed to the different sources in this term. It defines the starting CO2 level in our modeled area and how the transport from outside would affect it.

All the other terms (biospheric respiration, uptake, fossil fuel and nuclear 14CO2 emissions) are implemented with surface fluxes only (described explicitly in our section 2.2). That means that they are the recently added or removed quantities with a particular source/sink within the time and space of our simulation. And as such when we average the results for the 6 months we obtain a spacial map (for CO2ff much alike the one shown in Figure 4a, except there the scale is in ∆14CO2) in which for the lower 1 km of the atmosphere the average concentrations of CO2ff are between 1 and 18 ppm AND at the same time the average (spatial, since we average over the time) gradients in the concentrations of the CO2ff in the lower 1200 km are about 15 ppm.

From HS:

...My understanding now is that CO2ff in your paper is referring to the concentration of CO2ff that is above background levels of CO2 rather than absolute concentrations of CO2ff, thus please confirm my understanding is correct that your conclusion may be stated as "...the 6-month average [CO2 concentrations of fossil-fuel origin that are above background concentrations of CO2] in the lower 1 km of the atmosphere across Western Europe are between 1 to 18 ppm.", and that it is not possible to determine from your data the absolute concentrations of CO2 of fossil fuel origin [background + recently added].

Thanks once again for your assistance and please accept my sincere apologies.

From the author:

Thank you for the apology and in my turn, I apologize if I have been a bit too harsh in my response to you. Truth is, this is the first time when I had to deal with so much publicity regarding one of my works and it was very difficult to read the people's opinions of the article and its scientific merit, even when I realized that they were based mostly on the review only. As a scientist one must learn how to take criticism to one's work, but it doesn't necessary mean it is easier to do it.

I would also like to thank you for the general attempt to translate scientific words and work for the wider audience. Even if the review of my particular article was a bad example, a misstep, such work is crucial for the future of science as communication between scientists and the general public is a really important and extremely difficult task. One that most of the scientists can't do themselves either or are really poor at.

Your last paragraph describing the complicated fossil fuel/background relationship used in study is in fact totally correct. I am sorry that probably it is not going to be of use for your draft, however I am certain that there are other studies that investigate the issue you were trying to address.

I did mean that most authors would be eager to reply to questions about their work, especially immediately after an article has come out of publication. This is probably especially true for young researchers like me (not a Dr. yet), for which such contact provides the almost priceless feedback that their work is relevant or interesting for someone else than just other scientists.

42 comments:

There's a difference between the half-life of a CO2 molecule in the air (which is quite short), and the half life of a jump in CO2 intensity in the air (which is much longer). This is due to the constant exchange of CO2 between the surface and the air.

1. Segalstad et al find there is little difference (only a few years) between CO2 residence-time ~5-7 years and CO2 lifetime ~14-17 years. The notion that CO2 lifetime is "a thousand years or more" is based upon the highly-flawed IPCC Bern Model.

2. If CO2 lifetime was truly 1000+ years, fossil fuel derived CO2 should be much higher than 3.75%, as alarmists have claimed in the past using incorrect interpretations of C13/C14 ratios.

Agreed that the Bern model is flawed, as that is based on the saturation of the deep oceans. But the 5 years residence time is irrelevant and the 14 years lifetime is too short: that is based on the decay rate of the 14C spike of the 1950's atomic bomb tests. But the huge exchange with the deep oceans (~40 GtC/year) which is 500-1500 years old is a lot lower in 14C than the bomb spike, which makes the decay rate of 14C a lot faster than the decay rate of the human "spike", about a factor 3.

The 1,000 volcanoes that go off every year produce a major amount of the 166 gigatons produced on Earth every year. Man makes six of them, 3.22%, a fact that is in every geophysical text and reference.

As examples both melting ice and oceans release CO2 exponentially as they warm so increase is very easily explained by fact higher CO2 levels caused by temperature increase which has relatively little to do with CO2 levels...

Which also correlates with the fact that sea water contains CO2 in concentration 3,000 times that of the atmosphere. It takes only but a very slight change in ocean temperature to have a very large impact to atmospheric CO2 concentration. Precisely how atmospheric CO2 concentration has been around 3,000ppmv for the better part of the past 10,000 years.

Not saying that it's outgassing from the oceans, but Henry's law applies to Coca Cola too.

When the Coke warms up the CO2 bubbles away and you get flat pop.

There is also CO2 from volacanoes, something that has always made me feel uncomfortable about the measurements at Mauna Loa. Mauna Loa is the largest subaerial volcano in both mass and volume, and has historically been considered the largest volcano on Earth.

Over geological time volcanoes have been the main source of carbon dioxide and the oceans the main carbon sink. The current geological period is one of the lowest ever in CO2 density and plants are relatively starved of CO2. Possibly 1500 parts per million would suit plants much more than the measly 400 ppm they get now.

Squidly and others, it doesn't matter how much CO2 is in the oceans, what matters is the pressure difference. If you shake a 0.5, 1.0 or 1.5 liter bottle of Coke from the same batch at the same temperature, you will see the same pressure under the cork (slightly less in the smaller bottle due to the larger loss in the smaller amount of liquid). Henry's Law for seawater gives some 17 microatm more CO2 pressure for 1 K temperature increase. Thus an increase of ~17 ppmv in the atmosphere will fully compensate for the increase in temperature. Except if you think that the oceans have heated a lot more than 1 K since the LIA. That is the maximum increase from warming oceans... Vegetation goes the other way out, thus reducing the CO2 in the atmosphere for increasing temperatures (to about 8 ppmv/K in combination with the oceans)... The rest of the 100+ ppmv is from humans.

Correct, those are (estimated) emissions, yet the airborne fraction of man-made CO2 has been decreasing

http://hockeyschtick.blogspot.com/search?q=airborne+fraction+hansen

Both the airborne fraction decrease and that man-made CO2 emissions = current man-made CO2 levels at 3-4% suggest the rise of CO2 levels is primarily natural, and that CO2 lifetime is much less than the IPCC claims.

The IPCC has been publishing a lot of nonsense about CO2. Mount Pinatubo put out more new CO2 in a year than man did in 150 years or burning fossil fuel. That one volcano is responsible for most of the increase and every honest scientist paying attention knows it, but they also know from where the grant money comes and how much they want new taxes and more of our money.

IMHO modelers accounted for cooling between the 1940's and 1970's by really juicing volcanic aerosol emissions.Those aerosol quantities, heavily sulfur oxides were greatly exaggerated to fit the paradigm. Obviously, if SOx emissions were high so would be the CO2. Not commenting on this paper, just making a point of alarmist speak from both sides of the coin.

Did you notice this research is a simulation? As in a guess computed using a model. It is therefore not factual data about measurements collected in nature., so you can't present this as evidence of the sources of CO2.

The natural world is actually a net absorber of our CO2 emissions, which of course is why the oceans are becoming more acidic. Hence 100% of the rise in atmospheric CO2 since the pre-industrial is anthropogenic. That means current atmospheric CO2 is 30% anthropogenic, not 3%. An order of magnitude error in the study's results is quite impressive!

"The oceans are alkaline, not acidic, and scant evidence of a decrease in ocean pH."

All chemical compounds have a property called "acidity," and when it increases it is perfectly proper to say it is acidifying.

There is a symetric argument for alkalinity. But "debasification" is a mouthful, and obscures the point. There is ample evidence of a declining pH, with significantly more to come. It's basic chemistry.

The airborne fraction of human emissions varies from year to year, but didn't change much in average over the past 55 years, still 50-55% of human emissions:http://www.ferdinand-engelbeen.be/klimaat/klim_img/acc_co2_1900_cur.jpgandhttp://www.ferdinand-engelbeen.be/klimaat/klim_img/dco2_em2.jpgThat means that nature was a net sink of CO2 over the past at least 55 years.

The whole article is about the human part in the total carbon circulation, but that says next to nothing about the cause of the increase in the atmosphere, but the airborne fraction does...

If someone opens a supply valve in the circulation over a fountain that adds 1 l/minute while the circulation over the fountain is 1000 l/minute, the fountain certainly will overflow if he forgets to close the valve in time, even if that is only 0.1% of the supply...

BTW, the airborne fraction is a matter of two competing forces: the extra pressure of CO2 in the atmosphere compared to the "equilibrium" pressure for the current temperature, which forces more CO2 into the oceans (and plant uptake) and the effect of the extra pressure and temperature on the in/out fluxes.If we take the pressure difference as base, for the current 110 ppmv extra (231 GtC extra), the net result is ~2 ppmv (4.15 GtC) extra uptake by nature. Over the past 55 years that gives following curve of the airborne fraction as function of pCO2(atm) - pCO2(equi):http://www.ferdinand-engelbeen.be/klimaat/klim_img/dco2_em4.jpgStill largely within natural variability (here as 12-month running mean).

Appell: For a substance to become "more acidic" it has to be acidic i.e. pH < 7.0 to begin with. The more correct terminology for an alkaline substance such as seawater at pH ~8 is "less alkaline" or "less basic" because it will still be alkaline.

"Acidification" is off-topic for this thread - please comment on one of the many acidification threads, where you will also find many links demonstrating that there is no reliable evidence that ocean pH has actually decreased, and that the "basic chemistry" you claim to be so simple is actually quite complicated due to the presence of numerous buffering systems in the ocean.

Hansen's data shows that since 1960, man-made CO2 emissions have increased by a factor of 4, yet the airborne fraction of man-made CO2 has decreased 25% from 60% to 45%.

Quoting Hansen: "However, it is the dependence of the airborne fraction on fossil fuel emission rate that makes the post-2000 downturn of the airborne fraction particularly striking. The change of emission rate in 2000 from 1.5% yr-1 to 3.1% yr-1 (figure 1), other things being equal, would have caused a sharp increase of the airborne fraction (the simple reason being that a rapid source increase provides less time for carbon to be moved downward out of the ocean's upper layers)." But, it did not, according to Hansen because carbon sinks like CO2 fertilization of plants compensated by greening the planet. There is no evidence that such carbon sinks will stop compensating in the future, that the greening of the planet will not continue thanks to CO2 emissions.

The new paper in this post shows the total cumulative man-made contribution of CO2 is only 15%, due to erroneous prior assumptions about C14 levels in the atmosphere, failing to recognize the significant C14 source from nuclear power. Only ~11% of the increase in CO2 levels was from fossil fuels, 89% from primarily natural sources.

The significant decrease in airborne fraction over the past 50 years with man-made CO2 emissions increasing 400% clearly demonstrates man-made CO2 is not the primary source of the increase in CO2 levels. This new paper corroborates by showing current man-made CO2 levels are approximately equal to the percentage of man-made emissions, thus the primary cause of the CO2 increase is clearly not due to man.

As the lead author in the cited scientific article ( www.atmos-chem-phys.net/14/7273/2014/ ), I would like to address several key points of our study, which I believe were misunderstood by the author of this blog entry and are misleading the readers.

(1) The paper does not state that (quote from the blog) "only ~3.75% of atmospheric CO2 is man-made from burning of fossil fuels", this thought was constructed by the blog-writer and conclusions drawn from it are entirely his/her own.(2) The paper does not state that (quote from the blog) “only 15 ppm or ~11.5% of the increase (in CO2 since pre-industrial times) is of fossil fuel origin”. This again is a creation by the blog-writer.

As it is quite challenging to untangle the information extracted from our article and the conclusions, which the author of this blog is drawing from it, I hope for your patience in reading this undoubtedly long reply.

It might be easiest to point out first that the cited sentence („We find that the average gradients... “) from our abstract, which is possibly the centerpiece in this blog entry, is preceded in the article by several sentences explaining the temporal and spatial scope of our study – 6 summertime months in 2008 over Western Europe.

This explanation should already address the misconception that the cited 15 ppm of fossil fuel CO2 are the global average concentrations and cover the historical period since the pre-industrial era. Rather the opposite, those are the gradients in the newly added fossil fuel CO2 concentrations in Western Europe within the 6 month period covered in our study.

If you read the research article carefully you will find that the phrase used in both title and front-running paragraph of this blog entry ("only ~3.75% of atmospheric CO2 is man-made from burning of fossil fuels") is nowhere to be found in our article. This is because we aim at evaluating only the recently added anthropogenic CO2 to the atmosphere in a particular region of the world.

All the older (previously added, both anthropogenic and natural) CO2, as well as the CO2 being added during the 6 months of our study but outside of our research region are included in the term 'background CO2' in our study. This crucial point might have been overlooked by the blog-writer as we are using terminology and methods from previously published research (with provided references) that he/she might have not looked into. It is common and good practice in our field to use previously defined terminology.

I appreciate all the feedback and scepticism about our results as shown by the commenters here. I would, however, ask the author of the blog entry to try and be more careful in his summary of this and other scientific studies, especially when he makes claims about the findings that are nowhere in the article itself.

Dear (future Dr.) Bozhinova, thanks for the clarification! Anyway it has triggered a lot of discussion here and at WUWT. I hope you enjoyed the sometimes fierce arguments of all sides in the quite diverse group that the skeptics are. And I hope that you in your later work will remember that discussions are the part of science that keeps science healthy: a "consensus" kills scientific progress, critique and discussions do advance science...

BTW, was several times near Wageningen, biking through the Veluwe, beautiful in August-September... And I had a few discussions with Tom van Hoof from Wageningen University about the reliability of stomata data as CO2 proxy...